Band Gap on/off Switching of Silicene Superlattice

On the basis of density functional theory calculations with generalized gradient approximation, we have investigated in detail the cooperative effects of uniaxial strain and degenerate perturbation on manipulating the band gap in silicene. The uniaxial strain would split π bands into π_a and π_z bands, resulting in Dirac cone movement. Then, the hexagonal antidot would split π_a (π_z) bands into π_a1 and π_a2 (π_z1 and π_z2) bands, accounting for the band gap opening in the superlattices with the Dirac cone being folded to the Γ point, which is a different mechanism as compared to the sublattice equivalence breaking. The energy interval between the split π_a and π_z bands could be tuned to switch band gap on and off, suggesting a reversible switch between the high charge carrier velocity properties of massless Fermions attributed to the linear energy dispersion relation around the Dirac point and the high on/off properties associated with a sizable band gap. In addition, the gap width could be continuously tuned by manipulating strain, resulting in fascinating application potentials.